package snake;

public class SnakeNode {
 private int x;
 private int y;
 private SnakeNode next;
 private SnakeNode ahead;

 public SnakeNode() {
 }

 public SnakeNode(int x, int y) {
  super();
  this.x = x;
  this.y = y;
 }

 public int getX() {
  return x;
 }

 public void setX(int x) {
  this.x = x;
 }

 public int getY() {
  return y;
 }

 public void setY(int y) {
  this.y = y;
 }

 public SnakeNode getNext() {
  return next;
 }

 public void setNext(SnakeNode next) {
  this.next = next;
 }

 public SnakeNode getAhead() {
  return ahead;
 }

 public void setAhead(SnakeNode ahead) {
  this.ahead = ahead;
 }

}

package snake;

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.KeyEventPostProcessor;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
import java.util.Random;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

/**
 * Created by hackcoder on 15-3-11.
 */
public class Snake extends JFrame {
 private static final int rows = 60;
 private static final int columns = 80;

 // 方向
 private static final int UP = 1;
 private static final int RIGHT = 2;
 private static final int DOWN = 3;
 private static final int LEFT = 4;

 private static int DRIECTION_NOW = RIGHT;
 private static boolean isEat = false;

 private static int TAILX;
 private static int TAILY;

 private static SnakeNode snakeHeader = new SnakeNode();
 private static SnakeNode snakeTailer = snakeHeader;
 private static SnakeNode food = new SnakeNode();
 private static JLabel[] images = new JLabel[rows * columns];

 public static void main(String args[]) {
  snakeHeader.setX(new Random().nextInt(rows - 1));
  snakeHeader.setY(new Random().nextInt(columns - 1));
  Snake snake = new Snake();
  food = getFood();
  while (true) {
   try {
    next();
    // 吃到了食物
    if (food.getX() == snakeHeader.getX()
      && food.getY() == snakeHeader.getY()) {
     addTail();
     isEat = true;
    }
    //吃到食物，重新生成一个食物
    if (isEat) {
     food = getFood();
    }
    // 判断是否结束游戏
    if (judgeEND()) {
     JOptionPane.showMessageDialog(null, "游戏结束！", "游戏结束！",
       JOptionPane.ERROR_MESSAGE);
     break;
    }
    SnakeNode pNow = snakeHeader;
    while (pNow != null) {
     images[columns * pNow.getX() + pNow.getY()]
       .setIcon(new ImageIcon("image/black.jpg", ""));
     pNow = pNow.getNext();
    }
    images[columns * food.getX() + food.getY()]
      .setIcon(new ImageIcon("image/black.jpg", ""));
    Thread.sleep(100);
    // 清理
    pNow = snakeHeader;
    while (pNow != null) {
     images[columns * pNow.getX() + pNow.getY()]
       .setIcon(new ImageIcon("image/white.jpg", ""));
     pNow = pNow.getNext();
    }
    images[columns * food.getX() + food.getY()]
      .setIcon(new ImageIcon("image/white.jpg", ""));

    isEat = false;
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }
 }

 public Snake() {
  init();
  this.setBounds(80, 80, 400, 400);
  this.setVisible(true);
  setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
  // 添加全局键盘监听
  KeyboardFocusManager manager = KeyboardFocusManager
    .getCurrentKeyboardFocusManager();
  manager.addKeyEventPostProcessor((KeyEventPostProcessor) this
    .getMyKeyEventHandler());
 }

 /**
  * 初始化地图
  */
 public void init() {
  JPanel p = new JPanel(new GridLayout(rows, columns, 1, 1));
  setLayout(new BorderLayout());
  for (int x = 0; x < rows; x++) {
   for (int y = 0; y < columns; y++) {
    ImageIcon imageIcon;
    if (x == 0 || x == rows - 1 || y == 0 || y == columns - 1) {
     imageIcon = new ImageIcon("image/red.jpg", "");
    } else {
     imageIcon = new ImageIcon("image/white.jpg", "");
    }
    images[columns * x + y] = new JLabel(imageIcon);
    p.add(images[columns * x + y]);
   }
  }
  getContentPane().add(p, BorderLayout.CENTER);

 }

 /**
  * 键盘监听
  * 
  * @return
  */
 public KeyEventPostProcessor getMyKeyEventHandler() {
  return new KeyEventPostProcessor() {
   public boolean postProcessKeyEvent(KeyEvent e) {
    if (e.getID() != KeyEvent.KEY_PRESSED) {
     return false;
    }
    int keycode = e.getKeyCode();
    if (keycode == KeyEvent.VK_UP) {

     if (snakeHeader.getNext() != null) {
      // 判断方向是否可转
      int x1 = snakeHeader.getX();
      int y1 = snakeHeader.getY();
      int x2 = snakeHeader.getNext().getX();
      int y2 = snakeHeader.getNext().getY();
      if (y1 == y2 && x1 - x2 == 1) {
       return true;
      }
     }
     DRIECTION_NOW = UP;
    } else if (keycode == KeyEvent.VK_RIGHT) {
     if (snakeHeader.getNext() != null) {
      int x1 = snakeHeader.getX();
      int y1 = snakeHeader.getY();
      int x2 = snakeHeader.getNext().getX();
      int y2 = snakeHeader.getNext().getY();
      if (x1 == x2 && y2 - y1 == 1) {
       return true;
      }
     }
     DRIECTION_NOW = RIGHT;
    } else if (keycode == KeyEvent.VK_DOWN) {
     if (snakeHeader.getNext() != null) {
      int x1 = snakeHeader.getX();
      int y1 = snakeHeader.getY();
      int x2 = snakeHeader.getNext().getX();
      int y2 = snakeHeader.getNext().getY();
      if (y1 == y2 && x2 - x1 == 1) {
       return true;
      }
     }
     DRIECTION_NOW = DOWN;
    } else if (keycode == KeyEvent.VK_LEFT) {
     if (snakeHeader.getNext() != null) {
      int x1 = snakeHeader.getX();
      int y1 = snakeHeader.getY();
      int x2 = snakeHeader.getNext().getX();
      int y2 = snakeHeader.getNext().getY();
      if (x1 == x2 && y1 - y2 == 1) {
       return true;
      }
     }
     DRIECTION_NOW = LEFT;
    }
    return true;
   }
  };
 }

 /**
  * 计算贪吃蛇的方向及位移
  * 
  * @param header
  */
 public static void next() {
  if (snakeHeader == null)
   return;
  TAILX = snakeTailer.getX();
  TAILY = snakeTailer.getY();
  SnakeNode pNow = snakeTailer;
  while (pNow != null) {
   if (pNow == snakeHeader) {
    break;
   }
   pNow.setX(pNow.getAhead().getX());
   pNow.setY(pNow.getAhead().getY());
   pNow = pNow.getAhead();
  }

  if (DRIECTION_NOW == RIGHT) {
   snakeHeader.setY(snakeHeader.getY() + 1);
  } else if (DRIECTION_NOW == LEFT) {
   snakeHeader.setY(snakeHeader.getY() - 1);
  } else if (DRIECTION_NOW == UP) {
   snakeHeader.setX(snakeHeader.getX() - 1);
  } else if (DRIECTION_NOW == DOWN) {
   snakeHeader.setX(snakeHeader.getX() + 1);
  }
 }

 public static void addTail() {
  SnakeNode tail = new SnakeNode(TAILX, TAILY);
  snakeTailer.setNext(tail);
  tail.setAhead(snakeTailer);
  snakeTailer = snakeTailer.getNext();

 }

 public static SnakeNode getFood() {
  SnakeNode food = new SnakeNode();
  boolean flag = true;
  while (true) {
   int x = new Random().nextInt(rows);
   int y = new Random().nextInt(columns);
   if (x == 0 || x == rows - 1 || y == 0 || y == columns - 1) {
    continue;
   }
   SnakeNode pNow = snakeHeader;
   while (pNow != null) {
    if (x == pNow.getX() && y == pNow.getY()) {
     flag = false;
    }
    pNow = pNow.getNext();
   }
   if (flag) {
    food = new SnakeNode(x, y);
    break;
   }
  }
  return food;
 }

 public static boolean judgeEND() {
  //碰墙判断
  if (snakeHeader.getX() == 0 || snakeHeader.getX() == rows - 1
    || snakeHeader.getY() == 0 || snakeHeader.getY() == columns - 1) {
   return true;
  }
  //碰身体判断
  SnakeNode pNow = snakeHeader.getNext();
  while (pNow != null) {
   if (snakeHeader.getX() == pNow.getX()
     && snakeHeader.getY() == pNow.getY()) {
    System.out.println("=========碰到身体===========");
    return true;
   }
   pNow = pNow.getNext();
  }
  return false;
 }

}